Whatever Happened to That BBQ-ed F-35?
www.popularmechanics.com/military/a16126/air-force-charred-f-35/
Whatever Happened to That BBQ-ed F-35?
Eric Tegler
Jun 22, 2015 @ 11:17 AM
Between delays and cost overruns, the ongoing development of the Pentagon's next-gen fighter, the F-35, has been plagued by bad news. But none of those incidents were quite as jarring as what happened last June, when one of the Air Force's shiny new jets caught on fire.
The F-35A (the Air Force version of the Joint Strike Fighter) was launching from Eglin AFB in Florida as part of a two-plane training sortie. As the aircraft gathered speed on its takeoff roll, its Pratt & Whitney F135 engine stalled. Fire warning systems went off, the pilot aborted the takeoff, shut down the engine, and escaped the cockpit. The F-35, however, burned like a candle.
Now, one year later, the Air Force has decided what to do with the charred aircraft. As Joint Program Office spokesman Joe Dellavedova told Aviation Week: "It is likely parts will be returned to the F-35 spares inventory as appropriate. Other components of the aircraft will be evaluated for potential reuse in other aircraft or training systems." So another F-35A may shortly be flying with components from this baked Joint Strike Fighter.
However, the fixes required to keep the flame-up from happening again still haven't rolled out to all F-35s. After a fleet-wide grounding last summer, the Air Force and Pratt & Whitney traced the fire to a failure in the third-stage fan of the F135. Each fan stage rotates within the compressor casing, which is lined with an abradable strip to maintain tight clearances (essentially a seal) between the fan blade tips and the inner wall of the casing. In this particular aircraft, the blades were rubbing the strip far in excess of tolerances, apparently creating micro-cracking in the blades. The resulting fatigue caused the blades to fail, cutting through the compressor case, adjacent hydraulic lines, and the internal fuel tank.
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